feat: rolldownConfig

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Project	Deployment	Review	Updated (UTC)
nitro.build	Ready	Preview, Comment	Jan 21, 2026 6:02pm

[coderabbitai]

📝 Walkthrough

Walkthrough

Consolidates Rollup and Rolldown handling into a unified bundler abstraction: introduces getBundlerConfig, replaces ctx.rollupConfig with ctx.bundlerConfig, moves type exports into build.ts, and deletes the old getViteRollupConfig implementation. Changes adjust config merging, env exposure, and related types.

Changes

Cohort / File(s)	Summary
Bundler core & plugin integration src/build/vite/bundler.ts, src/build/vite/plugin.ts, src/build/vite/types.ts	Add getBundlerConfig; replace rollupConfig with bundlerConfig in plugin context and plugin flows; branch logic for Rollup vs Rolldown outputs; expose base build config.
Env & usage sites src/build/vite/env.ts	Replace uses of ctx.rollupConfig with ctx.bundlerConfig; introduce build.rolldownOptions; wire rolldownConfig/rollupConfig from bundler config into environment.
Rolldown config merging src/build/rolldown/config.ts	Extend merge order to include nitro.options.rolldownConfig, nitro.options.rollupConfig (back-compat cast), then existing config.
Removed legacy rollup implementation src/build/vite/rollup.ts	Delete former getViteRollupConfig implementation (function removed).
Type reorganization src/types/build.ts, src/types/config.ts, src/types/hooks.ts, src/types/index.ts	Move type exports to build.ts; add RolldownConfig type; add nitroOptions.rolldownConfig; update imports/exports to reflect new type locations; remove some legacy build types.
Defaults comment src/config/defaults.ts	Documentation/comment change: "Rollup" → "Builder".

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~60 minutes

Possibly related PRs

• refactor: vite@8 #3867: Refactors Vite/Rolldown integration and builder resolution — overlaps on bundler selection and plugin/config flow changes.
• refactor(vite): keep SSR bundle external dependencies #3854: Adjusts environment build options and noExternal/rollup options handling in env.ts — directly touches the same env wiring.
• fix: use module condition and main fields for bundling #3886: Modifies rolldown resolution/mainFields logic — related to rolldown config and merge behaviors updated here.

🚥 Pre-merge checks | ✅ 1 | ❌ 2

❌ Failed checks (1 warning, 1 inconclusive)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.
Description check	❓ Inconclusive	No pull request description was provided by the author, making it impossible to assess relevance to the changeset.	Please add a description explaining the purpose and scope of the rolldownConfig feature changes, including motivation and any breaking changes.

✅ Passed checks (1 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'feat: rolldownConfig' follows conventional commits format with proper type prefix and describes the main feature addition.

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✨ Finishing touches

• 📝 Generate docstrings

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch feat/rolldown-config

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commit: 5860fa5

[coderabbitai]

Actionable comments posted: 2

🤖 Fix all issues with AI agents

In `@src/build/vite/bundler.ts`:
- Around line 77-99: The current Rollup config creation in rollupConfig uses
defu with plugins: [inject(base.env.inject), alias({ entries: base.aliases })],
which overrides and drops any plugins present in commonConfig because defu does
not merge arrays; update the plugins value to explicitly concatenate
commonConfig.plugins (or an empty array) with the new plugins so base build
plugins (virtuals/replace/externals, etc.) are preserved — locate rollupConfig
and change the plugins assignment to merge commonConfig.plugins with
inject(base.env.inject) and alias({ entries: base.aliases }) (keep existing use
of defu, NODE_MODULES_RE, libChunkName, and other output settings intact).

In `@src/build/vite/plugin.ts`:
- Around line 184-186: The thrown Error message still says "Nitro rollup config"
while the code uses bundler terminology; update the message in the block that
checks ctx.bundlerConfig (the throw new Error(...) statement) to use consistent
phrasing such as "Nitro bundler config is not initialized yet." so it references
bundlerConfig instead of rollup config.